Development plans have a bad reputation because most of them are compliance documents: filled in during review season, containing three vague aspirations, and never opened again. A useful one is short, specific, and written for you rather than for the form.
Start from where you are, honestly
Before setting anything, write down what you are genuinely good at, what you are adequate at, and what you avoid. The last category is the most informative and the most often omitted.
Ask two colleagues what they would rely on you for and what they would not. Their answers are usually more accurate than your own assessment and occasionally uncomfortable.
Pick a direction before picking skills
Skills only make sense relative to a destination. Deciding you want to move toward technical depth, or toward managing people, or toward a different function changes entirely which gaps matter.
The direction can be provisional. It just has to exist, or the plan becomes a list of generally virtuous activities.
Choose two gaps, not eight
Identify the gaps between where you are and that direction, then pick the two with the highest leverage. Usually one is a hard skill and one is a way of working.
A plan with eight items is a wish list. A plan with two is something you can actually do while holding down a job.
Define what evidence would look like
For each gap, write what someone would observe if you had closed it. Not “improve at stakeholder management” but “run the quarterly review with the finance team without my manager present”.
This turns an abstraction into something with a date and a witness.
Choose activities that produce artefacts
Reading and courses are inputs and they are easy to complete without changing anything. Prefer activities that produce something: a document, a presentation, a shipped project, a decision you owned.
Artefacts can be shown in a review or an interview. Completed courses mostly cannot.
Name what you need from other people
Most development requires something from someone else: an opportunity, a piece of scope, an introduction, time from a colleague. If the plan does not say what you need and from whom, it silently assumes everything is within your control, which it is not.
This section is also what makes the plan useful in a conversation with your manager, because it tells them exactly how to help.
Set review dates and keep them
Two or three review points across the year, in your calendar, with the plan attached. At each one: what happened, what did not, what changes.
A plan without review dates is a document. A plan with them is a process.
Keep it to one page
If it is longer than a page you will not read it again. Direction, two gaps, evidence for each, activities, what you need from others, review dates. That fits comfortably and covers everything that matters.